Spray cleaning device for drying drum scraper blades



Jan. 19, 1965 D. EOLKIN 3,166,464

SPRAY CLEANING DEVICE FOR DRYING DRUM SCRAPER BLADES Filed on. 9. 1961 INVENTOR. Dove Eo l k i n BY United States Patent 3,166,464 SPRAY CLEANWG DEVICE FOR DRYING DRUM SCRAPER BLADES Dave Eolkin, Oakland, Calili, assignor to Gerber Products Company, Fremont, Mich. Filed Oct. 9, 1961, Ser. No. 143,617 2 Claims. ((1159-11) This invention relates to drum drying apparatus and to an improvement in the method of drum drying slurried materials. More particularly, it relates to an addition to the doctor or knife blade ofa drum drier in order to increase its efficiency.

In the accompanying drawings there is shown:

FIG. lschematically in side section, a pair of drum driers having doctor blades and .a conveyor in appropriate position and including the device provided by the present invention in cooperation with the doctor blades. 7

FIG. 2 shows the upper portion of the apparatus of FIG. 1 in end elevation.

In the art of drum drying materials such as food slurries, a problem has existed in relation to the build up of parts of the dried sheet on the doctor blades. This occurs over a period of time and, although the build up consists of relatively small pieces of the material being dried, the prolonged cumulative build up is deleterious to the overall operation of the apparatus.

The build up occur-s on the rear side of the doctor blade opposite to the cutting edge of the blade and adjacent to the drum drier. Since the material remains near the heated drum for a relatively long period of time, it tends to burn and harden. When the accumulation increases to the maximum size that will adhere to the blade, the excess falls ofi indiscriminantly in small pieces onto the drum surface as it rotates. The burned, hardened particles are then carried by the rotating drum and are recombined with fresh material ready to be dried. The finished product containing these recombined particles appear discolored in spots and, in the case of foodstuffs, has an undesirable flavor.

Another problem caused by the build up of particles on the rear side of the doctor or knife blade is in respect to the phenomenon known as double sheeting. This term is applied to the condition which results when the doctor blade fails to remove the sheet from the drum surface as the sheet reaches the blade. Consequently the drum revolves with the sheet, or a part thereof, still on its surface to pick up the next layer of material to be dried. A double layer of food or other material is the result.

The double sheeting problem frequently arises when the build up on the doctor blade becomes great enough to intercede between its cutting edge and the rotating drum to thereby lift the cutting edge from the drum surface. Double sheeting eventually leads to the necessity of shutting down the apparatus, cleaning it, and recommencing drying.

It is a principal object of the present invention to overcome all of the foregoing disadvantages of the prior apparatus. In essence, the solution to the above described problems is to provide means for spraying water on the rear side of the doctor blade adjacent the drum where the buildup of burned particles occurs, preferably spraying close to the line of contact between the knife and the drum. The water spray prevents build up on the back side of the knife and appears to keep the drum surface clean.

In a preferred embodiment. the present knife spray attachment is designed to be used with a pair of closely spaced parallel drum driers of the type adapted to dry slurried materials placed in the nip formed therebetween,

25 at the selected times.

3,166,464 Patented Jan. 19, 1965 "ice and which have a doctor blade associated with each drum for removing the dried materials from the drum surfaces.

The attachment comprises a water header disposed longi-l tudinally and substantially coextensive with each drum through the headers and spray nozzles only during those selected intervals.

Turning to the drawings, the preferred embodiment of the present device is schematically illustrated to include a pair of closely spaced parallel driers 1t), 11. The space above the nip 12 is used to hold a slurry of materials 13 to be dried on the surfaces of the drums 10, 11. Drying I occurs on the surfaces of the drums 1t 11 by heating these surfaces internally by suitable means such as steam placed in the interior of the drums.

The drums 10, 11 rotate toward each other in the direction of the arrows shown in FIG. 1. As the drums 10, llleave the nip 12 a thin layer 14 of slurry 13 remains on the drum surface until it reaches doctor blades 15, 16.

Cutting edges 17, 18 of doctor blades 15, 16 engage layer 14 that has been dried during its residence time on the drums 10, 11 while passing between nip 12 and blades 15, 16. When operating correctly, cutting edges 17, 18 part the dried film '14 from the drums 10, 11. The parted dried film or layer 14 is then transported away from the drum driers by a suitable transportation means such as a belt conveyor 19 for further processing.

As noted above, during operation, portions of the layer 1.4 build up on the rear sides 20, 21 of doctor blades 15, 16, respectively, and lead to the problems previously discussed. In accordance with the present invention, headers 22, 23 are disposed longitudinally and substantially coextensive with drums 10, 11, respectively, adjacent to their associated doctor blades 15, 16. Water headers 22, 23 contain spray nozzles 24, 25, respectively, in fluid communication therewith. Spray nozzles 24, 25 are positioned downwardly in the direction of the back sides 20, 21 of doctor blades 15, 16, respectively, so that a water spray 26 will impinge upon rear sides 20, 21. The spray of water removes the undesirable build up and results in a significantly more desirable and acceptable end product.

Research has shown that it is preferable to direct the water spray onto the rear sides 20, 21 intermittently as opposed to a constant flow. Accordingly, the improved method of the present invention comprises intermittently spraying the water on the appropriate parts of the doctor blades.

Optimum times for the spraying interval have been investigated. It has been found to be most beneficial to spray the water for about 1-2 seconds during every 15-30 second interval in most cases.

The intermittent spraying is automatically accomplished in the preferred embodiment by means of a timer and electro-valve mechanism of any type known in the art and shown schematically at 27. Timer and electro-valve mechanism 27 are conveniently positioned to cooperate with some portion of headers 22, 23 to start and stop the flow of water through the headers and spray nozzles 24, In this regard it is possible to have separate timing and valve means for each header or G one such unit in a common pipe from which headers 22, 23 may derive their water supply.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be practiced Within the spirit of the invention as limited only by the scope of the appended claims.

What is claimed is:

1. An improvement in the art of drum drying slurried foods comprising a pair of spaced apart but juxtaposed drying drums forming a nip to support a pool of slurry and arranged for rotation in opposite directions respectively and means to rotate the same, means to heat the drums to dry product on the surfaces thereof, means to supply product to the drum surfaces for drying thereon, a doctor blade for each drum arranged to remove dried product from each drum surface, each said doctor blade having a product cutting face and a back portion, water header means, means including said header to spray Water on the back portion of each said blade opposite said cutting face comprising nozzles arranged the full length of each said blade and disposed adjacent the back thereof, and means to supply water to said water header means.

2. An improvement in the art of drum drying slurried foods according to claim 1 and having means to provide intermittent Water spray from said nozzles to the back of each said blade.

References Cited in the file of this patent UNITED STATES PATENTS 1,317,100 Plant Sept. 23, 1919 2,886,101 Overton May 12, 1959 FOREIGN PATENTS 903,439 Germany Feb. 4, 1954 

1. AN IMPROVEMENT IN THE ART OF DRUM DRYING SLURRIED FOODS COKPRISING A PAIR OF SPACED APART BUT JUXTAPOSED DRYING DRUMS FORMING A NIP TO SUPPORT A POOL OF SLURRY AND ARRANGED FOR ROTATION IN OPPOSITE DIRECTIONS RESPECTIVELY AND MEANS TO ROTATE THE SAME, MEANS TO HEAT THE DRUMS TO DRY PRODUCT ON THE SURFACES THEREOF, MEANS TO SUPPLY PRODUCT TO THE DRUM SURFACES FOR DRYING THEREON, A DOCTOR BLADE FOR EACH DRUM ARRANGED TO REMOVE DRIED 